1. Field of the Invention
This invention relates generally to lifting/tilting devices, and more particularly to automated devices of this kind which are employed to raise garbage bins into the pour-in opening of a garbage truck.
2. Description of the Related Art Including Information Disclosed Under 37 CFR .sctn..sctn.1.97-1.99
More specifically, the invention relates to a safety circuit arrangement for lifting/tilting or tilting devices to empty containers of different sizes, in particular for lifting/tilting devices of garbage trucks with a control mechanism for the automatic emptying of the containers into collection bins and with at least two system contacts or system switches, in particular flap or acknowledgement signal switches, electrically connected, directly or indirectly, to the automatic control unit and actuated by the containers.
Garbage trucks are usually equipped with so-called automatic systems which, after the containers have been hung into the lifting/tilting device, raise them, empty them, possibly shake them and put them back on the ground. This automatic system is activated by a flap switch disposed on the lifting/tilting frame when the garbage container is hanging in the lifting/tilting frame and actuates the flap switch. The automatic system is then activated by a hand switch on the garbage truck. Under some circumstances, both the hand switch and the flap switch can be manipulated by the garbage collectors in order to accelerate the emptying process. Since such manipulation also puts the respective safety devices out of operation, the risk of accidents is considerably increased for the garbage collectors.
Known from EP-PS 1731 80 is a lifting/tilting device for emptying containers which is equipped with electric system contacts in the abutment area. Other system contacts are disposed on the center gripping plates of the gripping mechanism. A switching process can be triggered only by the combined actuation of at least three contacts, and such a switching process may consist in that the truck driver in the cab or a garbage collector working on the emptying device is given a signal that the actual emptying process can now be initiated. But it is also possible to utilize the simultaneous actuation of the three contacts for the automatic initiation of the actual emptying process.
But this arrangement still does not meet the desired stringent safety requirements because a manipulation of the system contacts can cause the safety provision to be put out of action again.